Chevron is now importing 250,000 barrels of crude per day from Venezuela.
Ione Wells travels to Sucre, where a lack of investment has hampered locals' prospects.
The US president wants American energy firms to start extracting the crude but they are reluctant.
The tanker, the Olina, is on multiple countries' sanctions list and is "suspected of carrying embargoed oil", US officials say.
The US has been ramping up pressure on the Venezuelan leader since Trump took office last January.
The US president also says the US intends to keep the tankers it has intercepted off the coast of Venezuela.
The move comes days after the US president said that he was ordering a blockade of sanctioned oil tankers entering and leaving Venezuela.
The move comes after US President Donald Trump ordered a "blockade" of sanctioned oil tankers entering and leaving Venezuela.
A tanker seized by the US is believed to be part of a "ghost fleet" used by Venezuela to evade oil sanctions.
